Many gasoline service stations require the installation of multi-fuel dispensers, each for dispensing a plurality of different grades or octane levels of gasoline products at each fueling position. Known dispensers or pumps typically include a separate hose, nozzle and nozzle boot for each fuel product or octane level of gasoline capable of being dispensed at an associated fueling position. Note that such dispensing systems are known as "wet hose systems", in which the hose remains filled with fuel from the most recent delivery. Through the use of such separate hoses, dispensers of the prior art avoid contamination of fuel being dispensed at a particular time, with fuel from a previous delivery that may remain in the hose at the termination of the last or prior to the last dispensing cycles. Buchanan et al U.S. Pat. No. 3,895,738 discloses such a dispenser, in which three fuel hoses, each for a different grade of gasoline, are used in a concentric hose configuration.
If the same hose is used for all fuel, the fuel remaining in the hose is of a different grade or octane level than fuel to be dispensed in the next subsequent dispensing cycle, contamination of the initial quantity of fuel delivered in the next dispensing cycle will occur through initial mixing of the desired fuel with the fuel remaining from the prior dispensing cycle. As long as the fuel being delivered in a given dispensing cycle is of a lower or equal octane or grade level than the residual fuel in the hose, a customer will receive at least the same or initially a higher grade of fuel, and suffer no detriment. However, if for example a lower octane gasoline was delivered in the last dispensing cycle, relative to fuel being delivered in a present dispensing cycle, through the same hose, a customer will initially receive a lower octane or grade level of fuel than requested. As previously mentioned, prior dispensing systems use separate hoses, nozzles and nozzle boots for each fuel available at a given fueling station, to avoid such fuel contamination during the initial phases of a given dispensing cycle.
There are many disadvantages in the use of discrete hoses for multi-fuel dispensers of the prior art. The cost of such dispensers is increased via the requirement for multiple hoses, each associated with an individual nozzle and nozzle boot. Also, the operation of such dispensers is substantially more complicated, and therefore more confusing for a user to operate. Another problem with such multi-hose dispensers is that the hoses sometimes become tangled with one another. The use of multiple hoses also compromises the appearance of such dispensers and increases the overall size and space requirements of the dispenser.